1. Field of the Invention
The present invention relates to communications networks. More particularly, this invention relates to communications network subscription services. Still more particularly, this invention relates to an improved method of selecting and accessing telecommunications network services.
2. Related Art
Modern homes and offices often connect to communications network subscription services for voice and data services. With increased business and consumer access to the Internet, subscriber demand for network bandwidth has increased substantially.
The expectation of "bandwidth-on-demand" was created by the Local Area Network (LAN). A LAN user shares a high-speed medium with many other users, having access to the full shared bandwidth on demand. In another version of bandwidth-on-demand, a user requests bandwidth, and is either granted the full request or is denied access completely, i.e. blocked. This second version is similar to a telephone call, where one either gets through or gets a busy signal.
Voice communications traffic can be forecasted and has a predictable character. Data communications traffic is quite different from voice communications. Data communications traffic can vary substantially over time. Key services and switching technologies in the emerging data market include Asynchronous Transfer Mode (ATM), Circuit switching, Frame relay, Internet Protocol (IP), N-ISDN, Private lines, SONET, Switched Multimegabit Data Service (SMDS) and X.25.
Users are moving towards using faster, larger, and more intelligent data communications networks, where the intelligence lies within the network, rather than outside the network. The term "intelligent network" is used to represent some level of "value-added" service provided by the network. Examples include intelligent routing decisions made within the network by route servers rather than predefined routes across the network and protocol conversion rather than just transparent protocol transport. Network intelligence can also mean a service offering based on centralized, intelligent, network-based devices. These devices act as information servers offering voice, video, imaging, routing and on-line service features. One example of such a server is a private on-line database service provider. Users want access to intelligent public data services in order to better leverage the intelligence within their own network. Users want flexible services which provide cost-effective network communications bandwidth.
With increased access to the Internet, Integrated Services Digital Network (ISDN) services have gained popularity. Modern ISDN services are available in several forms. ISDN Basic Rate Interface (BRI) is usually 144,000 bits per second and is designed for desktop computers, ISDN Primary Rate Service (PRI) is 1.544 Mbps DS1 or a 2.048 Mbps E-1 data rate channel and is designed for telephone switches, computer telephony and voice processing systems.
ISDN BRI service includes two 64 Kbps Bearer (B) channels for user data and one 16 Kbps Digital (D) channel for control, messaging, and network management. This service is commonly known as 2 B+D. ISDN PRI service in North America can be thought of as "enhanced T-1."
ISDN PRI service has 23 B channels and 1 D channel, each of which supports a full 64 Kbps. The D channel is used to carry signaling information for the other 23 B channels. Internationally, ISDN PRI has 30 B channels of 64 Kbps and two signaling channels. PRI was intended for use by higher bandwidth or shared customer devices such as a LAN, a personal computer, and a Private Branch Exchange (PBX).
After the definition of Broadband ISDN (B-ISDN), also known as Asynchronous Transfer Mode (ATM), the PRI and BRI ISDN standards are now referred to collectively as Narrowband ISDN (N-ISDN).
Another name for ISDN BRI channel is Digital Subscriber Line. Digital subscriber line is a three-channel digital line that links the ISDN customer's terminal to the telephone company switch with four ordinary copper telephone wires. The digital subscriber line is operated at the Basic Rate Interface (with two 64 Kbps circuit switched channels and one 16 Kbps packet switched channel). The digital subscriber line can carry both voice and data signals at the same time, in both directions. The digital subscriber line also carries the signaling data used for call information and customer data.
A digital loop carrier (hereafter DLC), refers to network transmission equipment used to provide network access. DLC is used in situations in which the cost of the terminating DLC equipment is more than offset by the savings in copper distribution accomplished by eliminating the need for as many individual copper pairs. DLC systems normally have two parts, a Central Office Terminal (COT) and a Remote terminal (RT). The central office terminal provides the multiplexing/demultiplexing function of individual voice signals to the composite multiplexed signal at the interface between the switching equipment and the DLC. The remote terminal provides the multiplexing/demultiplexing function at the interface between the individual subscriber pairs and the DLC.
The point of presence (POP) represents the physical place within a local access and transport area (LATA) where a long distance carrier or cellular provider interfaces with the network of the local exchange carrier (LEC) or local telephone company. A LATA is one of 16 local geographic areas in the U.S. within which local telephone companies may offer telecommunications services.
A digital subscriber loop (hereafter DSL), is the connection between an individual subscriber and a point of access to a shared data transport network or the point of presence. Often a digital subscriber loop is implemented by adapting an existing twisted wire pair that was previously intended as an analog telephone subscriber loop. Digital signals along a twisted wire pair may take the form of an ISDN n B+D signal, consisting of "n" number of bearer channels and a data channel for user-network signaling.
Data network services are categorized as being either connection-oriented or connectionless. Connection-oriented services involve establishing a connection between physical or logical end points of a network prior to the transfer of data. Examples of connection-oriented network services (CONS) are ATM and Frame Relay.
Connectionless data services provide end-to-end logical connectivity and do not require the establishment of a connection prior to data transfer. Examples of connectionless networking services (CLNS) are Internet Protocol (IP) and Switched Multimegabit Data Service (SMDS), mentioned above.
A given DSL subscriber may desire to carry video or other high rate data through the network using V.35, for example. This requires an interface device at the subscriber site to encode and couple the signal onto the subscriber loop. A similar device must also reside at the network end of the access loop to receive the signal and convert it to a form suitable for transport within the network which may use ATM, frame relay, TDM or other technologies.
A different subscriber may desire to use the DSL for intermittent or "bursty" data transfer. For example, Internet communications tend to be characterized by occasional bursts of large data transfers from point to point. This use of the access line requires a subscriber-side interface device that provides a standard connection to the subscriber's equipment such as an Ethernet 10-base-T (10bT) LAN. As before, the device must couple the data onto the access line to be received by a complementary interface device at the network access point. From here, the data can be packetized and sent about the network which, in this case, serves as a WAN. This transport may use a connectionless approach because delay and arrival sequence of the data packets is not as critical.
Modern DSLs are functionally limited in several ways. Suppose that a subscriber contracts to use a given access line, including its transmission facilities and terminating equipment, in order to access constant bit rate services. The given access line (i.e., including access medium layers 1, 2, and 3 of the OSI model) is typically dedicated to a single application, such as, e.g., to serve as a constant bit rate (CBR) line for voice. Subsequently, if the subscriber also wants to subscribe to adjustable bit rate (ABR) services, then a separate access line must be allocated to provide such service, along with its own terminating equipment and transmission facilities. If then the subscriber wants to subscribe to some other form of variable bit rate (VBR) service, then additional duplicative transmission facilities and terminating equipment are required. The service supported by each given access line is predetermined by the choice of equipment installed at either end of the access line, as well as the limits of the transmission facilities leased. For practical reasons, a single access line is dedicated to providing one mode of traffic. A separate access line including a separate transmission facility and separate terminating equipment at both the subscriber and network ends is thus required for every mode of communications. Accordingly, if the same subscriber wants to use multiple types of services, then duplicate hardware and software equipment is required including separate networks with separate transmission facilities and separate terminating equipment. The present approach is inflexible, duplicative and expensive. This redundant approach is costly to both subscribers and also to network providers, both in terms of capital outlay and in terms of ongoing maintenance costs.
Different facilities are required for different high speed access products such as High-speed DSL (HDSL), Symmetric DSL (SDSL), Asymmetric DSL (ADSL), coaxial cable modem services, etc. Examples include a cable modem for data access over a coaxial cable system. Another example is a 768 Kbps SDSL modem with synchronous interface for video conferencing, versus 768 Kbps SDSL modem with Ethernet 10bT interface for data traffic. Access to each additional service requires additional hardware and software at both the network carrier and customer subscriber ends. Moreover, additional transmission facilities are required between the network and subscriber ends of the loop. Both vendors and customers must deploy multiple systems to support multiple services, resulting in additional cost of service to the customer.
Another approach has been tried to address this need. This approach uses ATM from the network to the customer. This approach requires additional expense per line.
Yet another approach transfers constant bit rate traffic over connectionless protocols. This approach potentially degrades performance depending on the circumstances.
Another approach which has been used employs constant bit rate access for bursty connectionless traffic. This approach results in less efficient use of access/transport bandwidth than would be optimal.
What is needed then, is the ability to provide a common high speed physical access facility to be used to access multiple services in a cost-effective manner.